Titration of Acids in Nonaqueous Solvents

Fritz, James S.; Lisicki, N. M.

doi:10.1021/ac60052a012

Cited by 225 publications

(68 citation statements)

References 4 publications

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“…A few exampJ es of a related character have been reported previously by others [34, 351. h . Titrations in 4 :1 Benzene-Methanol Using Indicators B enzene-methanol, 4: 1 by volume, is currently popular as a solvent for nonaqueous titrations of carboxylic acids [36), p articularly if the acid is one of high molecular weight. As was shown in figure 4 (curve 1), when an equimolar mixture of b enzoic acid and diphenyl phosphate in this solvent was titrated potentiometrically with sodium m ethylate, th e separate end-points could b e lo cated satisfactorily.…”

Section: 2 Titrations Of Bases W Ith Diphenyl Phosphate Inmentioning

confidence: 99%

Titrations of bases with diphenyl phosphate in some aqueous and nonaqueous solvents

Davis¹,

Hetzer²

1955

J. RES. NATL. BUR. STAN.

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Successful titrations of various bases with diphenyl phosphate in benzene, methanol, water, and mixtures of these solvents have been performed, in some cases potentiometrically (using the glass, saturated calomel electrode-system) and in other cases using indicator dyes. Several of the dyes (bromophthalein magenta E, 5-phenyl-9-diethyl Nile blue, and t he anhydro-base of tamarack green and Victoria blue B) have not been used elsewhere as acidbase indicators. Diphenyl phosphate is shown to be a strong acid which is easily obtained and maintained as anhydrous crystals. It is not strong enough, however, to serve as a replacement for perchloric acid in titrations in acetic acid. Attention is called to the differing behavior of benzoic acid and diphenyl phosphate when the solvent is changed from water to methanol. Using a " nonleveling" solvent in place of water makes it possible to obtain separate, sharp end-points in titrating a mixture of two su ch acids. Other pertinent information about diphenyl phosphate is summarized.

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Section: 2 Titrations Of Bases W Ith Diphenyl Phosphate Inmentioning

confidence: 99%

Titrations of bases with diphenyl phosphate in some aqueous and nonaqueous solvents

Davis¹,

Hetzer²

1955

J. RES. NATL. BUR. STAN.

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“…9 Copolymerization of 1 with MA resulted in an alternating copolymer 2 (Scheme 1). The equimolar amount of 1 and MA in polymer 2 was confirmed by a titration of anhydride groups 12 (50 mol % in the polymer). Neither 1 nor MA was homopolymerized under the same reaction conditions.…”

Section: Synthesis and Characterization Of Polymermentioning

confidence: 82%

Depurination of synthetic poly(inosinic acid) analogues

Han

Cho

Lee

et al. 1999

J. Polym. Sci. A Polym. Chem.

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A poly(inosinic acid) analogue, poly{[1′‐(β‐hypoxanthine‐9‐yl)‐5′‐deoxy‐D‐erythro‐pent‐4′‐enofuranose]‐alt‐[maleic acid]} (4), was synthesized by the alternating copolymerization of nucleoside derivative 1 with maleic anhydride and subsequent hydrolysis. N‐Glycosidic bonds of the polymer were spontaneously hydrolyzed to liberate hypoxanthine from the polymer backbone in a buffer solution (pH 7.4) at room temperature. The depurination rate constant of the polymer at pH 7.4 and 37°C was measured to be 1.9 × 10−6 sec−1, which was 105‐fold higher than that (3 × 10−11 sec−1) of the depurination of DNA that occurred in the biological systems. The increase in the depurination rate was attributable to the high potential energy of the polymer caused by the crowded environment around the bases, so that the polymer was more susceptible to the hydrolysis. Since natural nucleic acids often have compact structures with the crowded environment around the bases by the intricate chain folding, the depurination may also be accelerated in a similar manner in the biological system. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3361–3365, 1999

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“…One of the carboxylic acid groups at the α-amino position is too weak to titrate in aqueous medium and hence the molar ratio found to be 1:1 (LNP: NaOH); where as in method C, both the carboxylic acid groups show enhanced acidic property in 3:1 benzene-methanol solvent medium when titrated against sodium methoxide using phenolphthalein as indicator as inferred by the reaction stiochiometry of 1:2 (LNP:MeONa). Benzene-methanol (3:1) solvent has been successfully used [32][33][34][35] in titrating many weak organic acids since the entire titration curves lies within the potential range of the solvent. Generally, benzene being a relatively neutral solvent of low dielectric constant is used in conjuction with any acidic or basic solvent in order to increase the sensitivity of the titration end-points and for differential titrations.…”

Section: Resultsmentioning

confidence: 99%

Titrimetric assay of lisinopril in aqueous and non-aqueous media

Basavaiah

Tharpa

Vinay³

2010

Eclet. Quim.

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Four simple titrimetric procedures are described for the determination of lisinopril (LNP) in bulk and in pharmaceuticals based on the neutralization of basic-amino and acidic carboxylic acid groups present in LNP. Method A is based on the neutralization of basic amino groups using perchloric acid as titrant in anhydrous acetic acid medium. Method B, method C and method D are based on neutralization of carboxylic acid group using NaOH, sodium methoxide and methanolic KOH, as titrants, respectively. Method A is applicable over 2.0-20.0 mg range and the calculations are based in the molar ratio of 1:2 (LNP:HClO4). Method B, method C and method D are applicable over 2.0-20.0 mg, 1.0-10.0 mg and 5.0-15.0 mg range, respectively, and their respective molar ratios are 1:1 (LNP:NaOH), 1:2 (LNP:CH3ONa) and 1:1 (LNP:KOH). Intraday and inter day accuracy and precision of the methods were evaluated and the results showed intra- and inter-day precision less than 2.7% (RSD), and accuracy of < 2.5% (RE). The developed methods were applied to determine LNP in tablets and the results were validated statistically by comparing the results with those of the reference method by applying the Student’s t-test and F-test. The accuracy was further ascertained by recovery studies via standard addition technique. No interferences from common tablet exipients was observed.

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Titration of Acids in Nonaqueous Solvents

Cited by 225 publications

References 4 publications

Titrations of bases with diphenyl phosphate in some aqueous and nonaqueous solvents

Titrations of bases with diphenyl phosphate in some aqueous and nonaqueous solvents

Depurination of synthetic poly(inosinic acid) analogues

Titrimetric assay of lisinopril in aqueous and non-aqueous media

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